Many of the 23 million individuals with heart failure (HF) worldwide receive daily, unpaid support from a family member or friend. Although HF and palliative care practice guidelines stipulate that support be provided to family caregivers, the evidence base to guide care for this population has not been comprehensively assessed. In order to appraise the state-of-the-science of HF family caregiving and recommend areas for future research, the aims of this review were to summarize (1) how caregivers influence patients, (2) the consequences of HF for caregivers, and (3) interventions directed at HF caregivers. We reviewed all literature to December 2015 in PubMed and CINAHL using the search terms "heart failure" AND "caregiver." Inclusion criteria dictated that studies report original research of HF family caregiving. Articles focused on children or instrument development or aggregated HF with other illnesses were excluded. We identified 120 studies, representing 5700 caregivers. Research on this population indicates that (1) caregiving situations vary widely with equally wide-ranging tasks for patients to help facilitate their health behaviors, psychological health and relationships, and quality of life (QoL); (2) caregivers have numerous unmet needs that fluctuate with patients' unpredictable medical status, are felt to be ignored by the formal healthcare system, and can lead to distress, burden, and reduced QoL; and (3) relatively few interventions have been developed and tested that effectively support HF family caregivers. We provide recommendations to progress the science forward in each of these areas that moves beyond descriptive work to intervention development and clinical trials testing.